Do I owe $$ to the rock supplier when I not hire them? I hired and paid the landscaping company. He didn’t pay supplier

I am a homeowner who hired a landscaping company. I aid them landscaping company $3100 of a $6200 estimate. He did part of the job and did not finish. He did not pay the Rock supplier. Now the rock supplier, who I did not hire, is asking me for payment of the rock. I had to hire another company to finish the job.